SET amps

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SET amps

Postby qguy » Mon Feb 23, 2004 9:29 am

what kind of music does a SET amp excel at...in comparison to a push pull amp such as the ST70

Are there different SET AMP .. aside from the output power, I mean is there big difference between a 2a3 Set and a SET which uses EL34 ?

thanks again...
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Postby arnoldc » Mon Feb 23, 2004 10:33 am

EL34 is not single ended triode and will never be. as for the difference in sound, it is subjective.
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Postby qguy » Mon Feb 23, 2004 11:40 am

ah okay..di pala purkit isang tube eh SET na ..hehehe also

what do you call those amp with 1 EL34 per side ?

and what tubes are "SET"...

As for the difference in sound your subjective comments would be much appreciated

thanks again

arnoldc wrote:EL34 is not single ended triode and will never be. as for the difference in sound, it is subjective.
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Postby arnoldc » Mon Feb 23, 2004 12:32 pm

SET = single ended triode

there are legitimate power triodes, such as 45 and variants, 300B, 25, 50, 2A3, 811, 825, and many many others.

EL34 is a Pentode. You can configure it as single ended pentode, and can be wired to full pentode, ultralinear, or pseudo triode.
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Postby SoFtCliPpEr » Sun Apr 25, 2004 10:37 pm

My UNISON S6 an integrated amp which uses 2 directly coupled TRIODE valves which has an output stage using 3 EL34 type valves per channel connected together in parallel configuration enabling it to operate in a SINGLE ended CLASS A ultralinear mode. This scenario gives me the benefit of driving lesser efficient yet more musical speakers with relative ease without sacrificing the SET advantage. Unlike the legitimate triodes which works best using high efficient speakers the illegitimate pentode EL34's can give you better dynamics using less efficient speakers for today's digital sources such as SACD or DVD-A.
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Postby arnoldc » Mon Apr 26, 2004 7:17 am

it is a common agreement that SET refers to the use of triode output valves, not drivers.
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Postby SoFtCliPpEr » Mon Apr 26, 2004 7:44 am

I submit :)
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Postby amandarae » Mon Apr 26, 2004 7:47 am

Boss arnoldc,

Since the 300 and 811 are of the same variants (or family), will the Super Tono 300B amp runs on an 811 tubes?

What needs to be done for it to do so? Or I am just spinning my own web here.

Thanks,
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Postby arnoldc » Mon Apr 26, 2004 8:35 am

@amandarae, not without modifications. we have to make sure that the driver will be able to drive the 811, and at the proper operating point.

you want to pursue this? let's see the options - if it is easy, why not, no? but if not, maybe building one from scratch will be better.
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Postby amandarae » Mon Apr 26, 2004 10:58 am

@amandarae, not without modifications. we have to make sure that the driver will be able to drive the 811, and at the proper operating point.

you want to pursue this? let's see the options - if it is easy, why not, no? but if not, maybe building one from scratch will be better.



Thanks sa explanation boss arnoldc, I really appreciate it. I know a litlle electronics, but does not have the schematic of the 300B so I have no reference whatsoever.

The idea came up because i know several amps where 2-3 tubes of the same variants can be use. But of course, there will be changes in the connections as well as the driver tube as you already mentioned. The Zen amps comes to mind as an example.

As for the 300B, the 6SL7's are the drivers right? How is it configured? Shunt regulated Push-Pull?

Oh well, when my 300B shows up, I'll shoot you an e-mail if what I "think" is possible and would not compromise the design. Of course, I will not do anything with out your blessing(and the DIY team) or if warranty will be voided as a result.

Like what my mother once said: "Mama raise no fool!!!"

thanks boss arnoldc
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Postby mozilla » Mon Apr 26, 2004 12:18 pm

Some like the SETs for their transparency & vocals especially if you mate it with the right speakers. A PP EL34 like the ST70 can produce audio magic as well if partnered with the right speakers.

When considering speakers for low powered SET amps, it is important to remember that sensitivity is not just the spec to look at. One must also look at efficiency as well. A sensitive speaker may have poor efficiency such that it will drive a low powered SET amp nuts.
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Postby ichabod » Mon Apr 26, 2004 1:19 pm

I remember Bobby Palcovic of Merlin speakers. He designs two sets of speakers of the same make or brand, one for tubes and the other for ss. One is underdamped the other over.

Such concerns should never go unnoticed if you want to optimize the sound of your audio.
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Postby SoFtCliPpEr » Mon Apr 26, 2004 1:56 pm

Guys maybe you can help me clear the field here. If speaker SENSITIVITY doesn't necessarily equate to it being EFFICIENT, is it correct to assume that we are talking about a loudspeaker with a sensitivity of 95DB and a nominal impedance of 2 ohms?? Is there such an animal of a transducer in the market?

If so for low powered SET the best specs to look into a speaker would be one with a sensitivity of 95DB SPL and an impedance of 8 OHMS. This would put me now in a dilemma
for my personal preference I like to use low sensitivity speakers about 87DB nothing above 90DB with a nominal impedance (W) of 8 and a minimal impedance of 4. Just to accomodate SETs do I now need to re-orient my preferences in speakers as well? Or would it be best for me to maintain my happy compromise using my EL34's.

Just asking :)
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Postby amandarae » Mon Apr 26, 2004 2:12 pm

SoFtCliPpEr,


Just to accomodate SETs do I now need to re-orient my preferences in speakers as well? Or would it be best for me to maintain my happy compromise using my EL34's



IMHO, No sir! Here is the solution if impedance is the main concern! Power, on the other hand is straight forward. If you have an 87 dB speaker and prefer listening at about 94dB for example, no matter what amps you use, you still need at least 7 dB plus minus how far your listening position will be with respect to the speakers (assuming that room interaction, acoustics, is not an issue).

http://www.zeroimpedance.com/


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Postby mozilla » Mon Apr 26, 2004 2:20 pm

Sensititvity refers to how loud a speaker will play for a given voltage level from an amplifier,( ie 95db/2.83V/m.) as meaured in db over voltage to a distance.

Efficiency refers to how "efficiently" a speaker converts the elec'l signal to acoustic power. In other words, how easy it is or isnt for an amp to maintain that voltage load on a speaker. This is normally discerned thru the impedance curve of the speaker. So a 95db/w/m speaker that hasa low impedance of say 2ohms at certain frequencies will strain the amp such that you will not be able to actually experience the 95db/w/m rating.

My 82db LS3/5a has ultra low sensitivity but is an easy load to drive for even SET amps due to its tube-friendly impedance curve.

This however, does not indicate how well the speaker-amp will sound.
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Postby SoFtCliPpEr » Mon Apr 26, 2004 3:05 pm

Thanks for the the impedance inputs can anyone give me an honest answer to my humble question quoted by amandarae?
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Postby mozilla » Mon Apr 26, 2004 3:17 pm

Joey,

To answer your question from my perspective, I use the LS3/5A. If I were to go SET, I would have to get another speaker.
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Postby amandarae » Mon Apr 26, 2004 3:20 pm

Boss, are you fond of single driver speakers? If so, maybe that is the answer. As far as I am concern, the SET experience without using a single driver speakers (horns, Transmission lines, pipes etc.) is not a "true" SET experience.

In my reading, most if not all SET fanatics have some form of single driver speakers.


So, yes you might re-orient your preference as far as speakers is concern if you want to dive in to what seasoned enthusiast call a true SET base(and real SET sound which is of course a matter of liking)) system. As for your EL34's, you can have that in a different set up if you want with a speakers you prefer being driven by it.

Like all things in life, there are some that works great only if you allow it to show its true colors. Anything in between.......will be un-civilized! :)


my $0.2......
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Postby ichabod » Mon Apr 26, 2004 3:24 pm

Well said Mozilla! Este Grant.

When I told Dan about the PMC DB 1 speakers, he supplied me some info on it after you did. But what he interestingly had looked for was the impedance curve, if it was indeed tube friendly. Dunno if he found it.

Any how, that's the beauty of a low senz speakers like the LS 3/5a. But not all of them are created equal. I know the Harbeth P3 dips (suppose to replace the LS) to 2-3 ohms unless I've heard wrongly.

At nearfield listening, the LS can be deafening enough at a max of 95db. Most program material including a live concert can play between 87 to 92 dB, and at that volume they sound as natural and comfortable on the ears like I'm in a concert hall.

Somehow, low senz. high powered amps. Hi senz. low powered set amps, all seems equal to me unless Arnold C can help why it ain't so audibly speaking.
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Postby SoFtCliPpEr » Mon Apr 26, 2004 3:24 pm

The magic numbers for me is 87DB SPL Impedance Nominal 8 and Minimum 4.

Question: Will a SET amp at let's say 5W per channel do it for me or will my present EL34 juiced Class A integrated amp (35W) take me to the music in a better way? :)
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